This review of women's participation in the legal system as expert witnesses examines the empirical literature on the perceived credibility and persuasiveness of women compared with men experts. The effects of expert gender are complex and sometimes depend on the circumstances of the case. Some studies find no differences, some find favorable effects for women and others for men, and still others find that expert gender interacts with other circumstances of the case. The findings are interpreted through social role theory and the role incongruity theory of prejudice. Future directions for research are identified and implications are considered for attorneys who select and prepare expert witnesses. Suggestions for men's and women's behavior as expert witnesses are provided. Copyright © 2014 John Wiley & Sons, Ltd.